There have been many attempts to achieve an insulating material having down-like qualities for use in insulated articles such as clothing, sleeping bags, comforters, and the like. Prior efforts to develop a feasible material have most often yielded materials that are too heavy and dense to be considered down-like and/or are difficult to blow through conventional equipment.
U.S. Pat. No. 5,624,742 to Babbitt et al. describes a blowing insulation that comprises a blend of first and second insulating (glass) fiber materials. One of the groups of fibers is smaller in size for filling the voids between the fibers of the larger group.
U.S. Pat. No. 3,892,919 to Miller describes a filling material using larger cylindrical or spherical formed fiber bodies along with feathery formed bodies which are mixed together, with the latter relied upon to fill the voids.
U.S. Pat. No. 4,167,604 to Aldrich describes an improved thermal insulation material that is a blend of down and synthetic staple fiber formed from hollow polyester filaments which may be treated with silicone and formed into a carded web.
U.S. Pat. No. 4,248,927 to Liebmann describes an insulating material comprising a combination of natural feathers and downs, and synthetic polyesters formed into web.
U.S. Pat. No. 4,468,336 to Smith describes loose fill insulation that is blown into spaces. The insulation material comprises a mixture of loose fill cellulosic insulation mixed with a staple fiber.
U.S. Pat. No. 5,057,168 to Muncrief describes insulation formed by blending binder fibers with insulative fibers. The insulative fibers are selected from the group consisting of synthetic and natural fibers formed into a batt which may be cut into any desired shape.
U.S. Pat. No 5,458,971 to Hernandez et al. describes a fiber blend useful as a fiberfill in garments. The fiberfill blend comprises crimped hollow polyester fiber and crimped binder fibers.
U.S. Pat. No. 4,040,371 to Cooper et al describes a polyester fiber filling material comprising a blend of polyester staple fibers with organic staple fibers.
U.S. Pat. No. 5,492,580 to Frank describes a material formed by blending a mix of first thermoplastic, thermoset, inorganic, or organic fibers with second thermoplastic fibers.
U.S. Pat. No. 4,588,635 to Donovan discloses a superior synthetic down and has particular reference to light-weight thermal insulation systems which can be achieved by the use of fine fibers in low density assemblies and describes a range of fiber mixtures that, when used to fabricate an insulating batt, provides advantageous, down-like qualities such as a high warmth-to-weight ratio, a soft hand, and good compressional recovery. This material approaches, and in some cases might even exceed, the thermal insulating properties of natural down. From a mechanical standpoint however, extremely fine fibers suffer from deficiencies of rigidity and strength that make them difficult to product manipulate and use. Recovery properties of such a synthetic insulator material are enhanced at larger fiber diameter but an increase in the large fiber component will seriously reduce the thermal insulating properties overall. The problems associated with mechanical stability of fine fiber assemblies are excerbated in the wet condition since surface tension forces associated with the presence of capillary water are considerably greater than those due to gravitational forces or other normal-use loading and they have a much more deleterious effect on the structure. Unlike waterfowl down, the disclosed fiber combination described provides excellent resistance to wetting.
U.S. Pat. No. 4,992,327 to Donovan et al. discloses the use of binder fiber components to improve insulator integrity without compromising desired attributes. More specifically, the invention disclosed therein relates to synthetic fiber thermal insulator material in the form of a cohesive fiber structure, which structure comprises an assemblage of: (a) from 70 to 95 weight percent of synthetic polymeric microfibers having a diameter of from 3 to 12 microns; and (b) from 5 to 30 weight percent of synthetic polymeric macrofibers having a diameter of 12 to 50 microns, characterized in that at least some of the fibers are bonded at their contact points, the bonding being such that the density of the resultant structure is within the range 3 to 16 kg/m.sup.3, the thermal insulating properties of the bonded assemblage being equal to or not substantially less than the thermal insulating properties of a comparable unbonded assemblage. The reference also describes a down-like cluster form of the preferred fiber blends. The distinct performance advantages of the cluster form over the batt form are also disclosed.
However, prior art clusters often are generally hand-fabricated in a slow, tedious, batch process. Furthermore, the prior art materials are not easily blowable material which can be used with conventional manufacturing equipment. Therefore, there is a need for a blowable material which may be used as a partial or full replacer for down, and which may be manufactured and blown using conventional equipment.